travelog 72

Birth of a Flight Artist

This time we want to tell our European readers about an animal that they know at best from photos or a vacation in the Americas, the hummingbird. American visitors to our website probably know hummingbirds and might have seen them in their own backyards or even have put up a hummingbird feeder, but we're sure that the majority hasn't witnessed the birth and growing up of a hummingbird. It was pure luck that we discovered a hummingbird nest with two eggs and had the opportunity to observe the brooding and fledging of a hummingbird.

Hummingbirds are commonly described as small birds with colorful feathers and long beaks but they're actually very different from each other. There are about 340 species of hummingbirds that belong into the family Trochilidae. The smallest hummingbird, the Bee Hummingbird (Mellisuga helenae), occurs in Cuba and, with its 1,8 grams, is one of the smallest warm-blooded animals. The largest one, appropriately named Giant Hummingbird (Patagona gigas), occurs in South America and weighs up to 24 grams, more than many songbirds. The average weight of a hummingbird is about 3 grams. Its plumage can be relatively boring and colorless but also bright and extremely colorful. The beak is also very different in the various species. Sometimes it's straight and pretty short like a normal bird beak, other times the beak can measure half of the hummingbirds body lenght. There's a fundamental difference between hummingbirds and other birds, and that's its flight. Hummingbirds can hover in the air, similar to insects. Other birds can hover too, but only for a few beats of their wings. Hummingbirds on the other hand can hover for a very long time. Effortlessly they can also fly backwards, up and down, and from one side to the other. Their wings move between 15-80 times per second. This produces the humming sound that gave the hummingbird its name in many languages. The Mayas called the hummingbirds "tz'unun", in Spanish it's sometimes called "zumbador". There are also common names that refer to the connection of hummingbirds with flowers as in the Spanish "chuparosa", the Portuguese "beijaflor", or the French "suce-fleur".

Hummingbirds occur only in North and South America where they can be found from southern Alaska and Canada down to Tierra del Fuego. The majority of the hummingbirds is found in tropical Central or South America. There's one animal in Europe that remotely resembles a hummingbird, the Hummingbird Hawk-moth, or Macroglossum stellatarum. This moth is active during the day, a fact that is very untypical of moths. It hovers in the air similar to a hummingbird and also produces a humming sound while flying.

The plumage of hummingbirds is almost always iridescent. Gleaming and changing color hues are produced by the pigment melanin which usually absorbs light to produce shades of black, gray and brown. In the hummingbirds plumage melanin reflects and breaks the light. This pigment occurs in flat particles which include extremely small air bubbles acting like prisms and breaking up white light into its color components before these are reflected back through the feather. The iridescent feather colors change with the position of the feather, the observer and the source of light. That's why the throat of a hummingbird can seem to be scarlet red, red-orange, yellow-orange, golden colored or even blackish. Certain hummingbird species sport an iridescent blue gleaming breast, others a purple cap on the head. It all depends on how the light touches the bird.

Hummingbirds feed on nectar and insects. The nectar of flowers visited by hummingbirds are rich in sugar, especially sucrose. With the exception of insects, hummingbirds have the most efficient metabolism in the animal world. This enables them to sustain the fast beating of their wings. To survive, the small birds must consume food of up to 1 1/2 times the weight of their body per day. Contrary to the myth that hummingbirds are only attracted to the color red, they feed on flowers of every color.

Particularly important is the highest nectar production and the highest concentration of sugar. Hummingbirds are important pollinators because they can cover much larger distances than insects and fly in bad weather. The typical flower is a long narrow tube and varies in shades of red, orange and pink. Red is not a very attractive color to bees thus they're no competition for the hummers. Tubular flowers are more difficult to pollinate for insects, as well. These flowers are normally rich in sucrose, contrary to the ones pollinated by insects which are richer in glucose and fructose. By the way, we humans like sucrose a lot better than the "easy" sugars too! Hummingbirds also feed on insects such as flies, moskitoes and aphids which contain essential nutrients. Particularly at dusk hummers drink as much as possible to survive the night. The small birds digest their accumulated reserves while they sleep. Stress such as low temperatures, long nights or not enough food lead to a condition called torpor. It's a condition similar to the hibernating of other animals in which breathing, pulse and body temperature are drastically reduced. This is a very efficient way of saving energy but it also makes the bird more prone to dangers because it can't react quickly.

Hummingbirds are extremely asocial birds. They vehemently defend their territory and nectar sources against intruders. Nest building, hatching and raising of the young birds is entierly up to the mother. Female hummingbirds build a nest before they mate. Normally they lay two eggs which look tiny to us but are pretty big compared to the size of the mother. Brooding takes from 12 to 22 days. To feed the young birds the mother regurgitates partially digested insects into their mouths. 9 to 12 days after hatching, the young birds have enough feathers to be able to maintain their body temperature. 18 to 28 days after hatching, they finally leave the nest though they're still dependent on the mother for another 1 to 4 weeks. She keeps feeding them and shows them how to catch insects and where to find nectar. Hummingbirds live for about 3-5 years but even 12 year old birds have been known.

Now back to our hummingbird nest. If our hummingbird mother is not busy searching for nectar, she snuggles up in her small nest or brings new feathers, dry grass or other soft material that she carefully incorporates into her nest. Other hummingbirds are chased away with loud chirpings. She doesn't like our presence too much either but we're not giving up as easily as her kin. Every day we check the nest twice to see if a bird has hatched but we're disappointed for a long time. Suddenly one afternoon we discover a strange little thing in the nest. One of the eggshells is broken, the other egg still untouched. The strange little thing turns out to be a just hatched hummingbird. The poor little thing is completely naked, tiny and has a white point on his head which is only recognizable as such thanks to a tuft of hairs that looks like a comic book illustration. Whatever happened to the second egg, we don't know. It seems as if another bird never hatched. The first-born probably committed brother or sister murder to have the full attention of the mother.

Our little bird develops marvellously and incredibly fast. Soon a real bird head is recognizable and the tuft of feathers on its head is thicker and its body soon is covered with feathers too. Even the beak starts to develop and now it's easy to see where the front and rear ends of our offspring are. Mama hummingbird is now very busy looking for food and stays away from the nest for longer periods of time. The little one seems to get accostumed to our presence. After all we climb the ladder every day to take pictures. Amazingly fast our young bird looks like a real hummingbird in miniature size and after about 3 weeks he's fully fledged and leaves the nest. Later we can only spot him at flowers because he's still a lot smaller than the other hummingbirds.

Hummingbirds are fascinating and you can spend hours watching them. To find a nest and see a young bird hatch and grow up is an unforgettable experience. By the way, to find a hummingbird's nest brings good luck according to the Mexican popular belief. Well, then lets see what good luck we'll have!

September 2006

Julia Etter & Martin Kristen